From 355d3d76b4825d2ed38ece36c23da1e44fdc9d5c Mon Sep 17 00:00:00 2001
From: Bill Currie <bill@taniwha.org>
Date: Fri, 29 Sep 2023 13:13:35 +0900
Subject: [PATCH] [qfcc] Clean up nested scale handling

This is incomplete in that the handling needs to be moved into
distribute_product, but the infrastructure is there without breaking
anything.
---
 tools/qfcc/source/expr_algebra.c | 61 +++++++++++++++++++++-----------
 1 file changed, 41 insertions(+), 20 deletions(-)

diff --git a/tools/qfcc/source/expr_algebra.c b/tools/qfcc/source/expr_algebra.c
index b2311a75d..8588102f3 100644
--- a/tools/qfcc/source/expr_algebra.c
+++ b/tools/qfcc/source/expr_algebra.c
@@ -732,6 +732,29 @@ distribute_product (type_t *type, int op, const expr_t *a, const expr_t *b,
 	}
 }
 
+static const expr_t *scale_expr (type_t *type,
+								 const expr_t *a, const expr_t *b);
+
+static const expr_t *
+extract_scale (const expr_t **expr, const expr_t *prod)
+{
+	if (is_scale (*expr)) {
+		auto s = (*expr)->expr.e2;
+		prod = prod ? scale_expr (get_type (prod), prod, s) : s;
+		*expr = (*expr)->expr.e1;
+	}
+	return prod;
+}
+
+static const expr_t *
+apply_scale (type_t *type, const expr_t *expr, const expr_t *prod)
+{
+	if (expr && prod) {
+		expr = scale_expr (type, expr, prod);
+	}
+	return expr;
+}
+
 static const expr_t *
 scale_expr (type_t *type, const expr_t *a, const expr_t *b)
 {
@@ -745,14 +768,13 @@ scale_expr (type_t *type, const expr_t *a, const expr_t *b)
 	if (!is_real (get_type (b))) {
 		internal_error (b, "not a real scalar type");
 	}
-	int  op = is_scalar (get_type (a)) ? '*' : SCALE;
 
-	if (is_scale (a)) {
-		// covert scale (scale (X, y), z) to scale (X, y*z)
-		b = scale_expr (get_type (b), b, a->expr.e2);
-		a = a->expr.e1;
+	const expr_t *prod = extract_scale (&a, b);
+	if (prod) {
+		b = prod;
 	}
 
+	int  op = is_scalar (get_type (a)) ? '*' : SCALE;
 	auto scale = distribute_product (type, op, a, b, 0);
 	if (!scale) {
 		return 0;
@@ -791,23 +813,11 @@ dot_expr (type_t *type, const expr_t *a, const expr_t *b)
 	}
 
 	const expr_t *prod = 0;
-	if (is_scale (a)) {
-		prod = a->expr.e2;
-		a = a->expr.e1;
-	}
-	if (is_scale (b)) {
-		auto s = b->expr.e2;
-		prod = prod ? scale_expr (get_type (prod), prod, s) : s;
-		b = b->expr.e1;
-	}
+	prod = extract_scale (&a, prod);
+	prod = extract_scale (&b, prod);
 
 	auto dot = distribute_product (type, DOT, a, b, reject_dot);
-	if (!dot) {
-		return 0;
-	}
-	if (prod) {
-		dot = scale_expr (type, dot, prod);
-	}
+	dot = apply_scale (type, dot, prod);
 	return dot;
 }
 
@@ -825,7 +835,12 @@ cross_expr (type_t *type, const expr_t *a, const expr_t *b)
 		return 0;
 	}
 
+	const expr_t *prod = 0;
+	prod = extract_scale (&a, prod);
+	prod = extract_scale (&b, prod);
+
 	auto cross = distribute_product (type, CROSS, a, b, reject_cross);
+	cross = apply_scale (type, cross, prod);
 	return cross;
 }
 
@@ -842,7 +857,13 @@ wedge_expr (type_t *type, const expr_t *a, const expr_t *b)
 		// propagated zero
 		return 0;
 	}
+
+	const expr_t *prod = 0;
+	prod = extract_scale (&a, prod);
+	prod = extract_scale (&b, prod);
+
 	auto wedge = distribute_product (type, WEDGE, a, b, reject_wedge);
+	wedge = apply_scale (type, wedge, prod);
 	return wedge;
 }